JPH05166539A - Internal structure of battery - Google Patents

Abstract

PURPOSE:To provide battery structure of high capacity in which a positive electrode and a negative electrode, respectively formed by sticking active materials to metal foils, are wound into a roll shape in such a manner that the active materials are arranged opposing to each other via a separator. CONSTITUTION:A metal foil 3 or 4 of either of a positive and a negative electrodes is exposed at the outermost peripheral part of a roll, and a conductive spring 7 is interposed between the metal foil 3 or 4 and a battery can 6. With this constitution, electricity can be stably taken out through a battery can wall and therefore a space inside the battery can be effectively utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery structure, particularly to a battery structure suitable for non-aqueous systems. More specifically, the present invention comprises a positive electrode and a negative electrode each formed of a metal foil having an active material attached to the surface thereof, and these positive electrode and negative electrode are superposed with a separator interposed therebetween, and rolled up in a roll shape. output,
The present invention relates to improvement of the structure of a battery, especially a non-aqueous battery, which can extract electric energy with a high energy density.

[0002]

2. Description of the Related Art In a battery in which positive and negative electrodes are opposed to each other with a separator interposed therebetween, the output characteristics of the battery are generally proportional to the area of the positive and negative electrodes facing each other. Should be held as wide as possible.

Particularly in the case of a non-aqueous battery, it is necessary to secure a larger area because the electrolysis solution itself used has a relatively low conductivity. Therefore, in order to efficiently obtain a large area for the electrodes, it is effective to use a thin metal foil as a current collector, to which each electrode is formed by adhering the active material thereto, and then to wind it in a roll shape. Is.
For example, Japanese Unexamined Patent Publication No. 60-253157 discloses a non-aqueous secondary battery of this type which uses an aluminum foil having a thickness of 1 to 100 μm and has a high output and a high energy density.

However, when the active material is attached to both sides of the metal foil current collector and the positive and negative electrodes are wound in a roll shape, the active material opposite to the active material outside the outermost peripheral portion is used. Since it does not exist, there arises a problem that it hardly functions. Moreover, in the battery having such a structure, the length per one round becomes the longest in the outermost peripheral portion, so that the volume occupied by the outermost peripheral portion which does not substantially function becomes an unacceptable ratio.

In order to solve such a problem, the present inventors have previously established that, of the positive electrode and the negative electrode, at least one of the positive electrode and the negative electrode, which is the outermost peripheral portion in the state wound in a roll shape, is only on one side. The active material of the two metal foils having the active material adhered thereto is integrally formed by adhering the surfaces not adhered to each other, and the metal foil which is the outer side of the integrally formed pole is the inner side. A battery structure was invented and a patent application has been filed, which is characterized in that the outermost peripheral portion is surrounded by the inner metal foil, which is shorter than the metal foil by about one circumference. 2-269607).

[0006]

In the battery in which the outermost peripheral portion is surrounded by the metal foil, the outermost peripheral portion is directly contacted with the inner wall of the metal battery can, so that electric energy can be transferred through the battery can wall. You can take it out. By doing so, the tab material for extracting electric energy can be omitted, and the space in the battery can can be used more effectively.

However, if the electrode body having the outermost peripheral portion surrounded by the metal foil is simply inserted into the battery can, the electrical contact between the outermost peripheral portion and the inner wall of the battery can is insufficient, so that stable electrical conduction is achieved. I couldn't get the energy out.

The present invention is a battery formed by winding a positive electrode and a negative electrode, each of which is made by attaching an active material to a metal foil, in a roll shape so that the active materials face each other with a separator interposed therebetween. In the structure described above, the metal foil of either the positive electrode or the negative electrode is exposed at the outermost peripheral portion of the roll, the outer peripheral portion and the inner wall of the metal battery can are surely brought into contact with each other, and stable through the inner wall of the battery can. It is an object of the present invention to provide a high-capacity battery structure that can take out electric energy from a battery.

[0009]

In order to achieve the above object, the present invention provides a conductive spring between the outermost peripheral portion of the roll where the metal foil is exposed and the inner wall of the metal battery can. Is characterized by. Hereinafter, the present invention will be specifically described.

The conductive spring used in the present invention is preferably a thin metal plate having rigidity, and specifically, hard copper or a copper alloy such as phosphor bronze, stainless steel,
Nickel etc. are illustrated. The thickness of the spring is
10 μm to 300 μm is suitable. If the thickness is less than 10 μm, the spring force is insufficient and stable electrical contact cannot be obtained. If it is thicker than 300 μm, the rigidity is too strong and the roll may be damaged when it is inserted into the battery can, and the volume in the battery can is wasted, which is not preferable.

The shape of the spring is not particularly limited, but is generally rectangular, and the long side is inserted with the lengthwise direction of the battery. The long side is approximately several mm from the length of the roll
The length may be shortened, and the short side may be about 1/5 to 3 times, preferably about 1/5 to 3/2 times the diameter of the battery can. It is also effective to preform the spring so that the bottom of the roll can be easily inserted into the battery can. The number of springs to be inserted may be one or plural.

The positive electrode active material used in the present invention is not particularly limited as long as it is capable of dedoping and doping lithium ions. For example, in a positive electrode active material of a secondary battery, lithium cobalt oxide, lithium manganese oxide, lithium chromium oxide, lithium vanadium oxide, lithium molybdenum oxide, lithium molybdenum sulfide, lithium titanium oxide, lithium titanium sulfide. Examples thereof include complex oxides of metals. Preferred are lithium cobalt oxide and lithium manganese oxide having a structure of LiCoO ₂ . Further, examples of the positive electrode active material of the primary battery include lithium cobalt oxide and manganese oxide.

The negative electrode active material used in the present invention is not particularly limited as long as it is capable of dedoping and doping lithium ions. For example, in the negative electrode active material of a secondary battery, any carbonaceous material such as graphite, pitch coke, needle coke, petroleum coke, organic polymer fired body (phenol resin, furan resin, polyacrylonitrile, etc.), etc. Can be used. Also,
Similar carbonaceous materials are available for primary batteries.

As the metal foil as the current collector, copper, nickel, stainless steel or the like having a thickness of about 100 μm to 5 μm is used for the negative electrode. Preferred are copper and stainless steel. Further, aluminum or the like having a thickness of about 100 μm to 5 μm is used for the positive electrode.

Examples of the binder include Teflon, polyvinylidene fluoride, polyethylene, polystyrene and the like. The thickness of the negative electrode active material and the binder attached to the metal foil is generally 60 to 750 μm on each side.

As the separator used in the present invention, one type of microporous film made of polyolefin such as polyethylene or polypropylene, or one type or a laminated type of two or more types thereof can be used. Further, non-woven fabrics such as polyolefin, polyester, polyamide, and cellulose can be used alone or in combination with the above porous membrane.

The non-aqueous electrolyte solution used in the present invention contains, for example, LiClO ₄ , LiAsPF ₆ , L as an electrolyte.
Any one of lithium salts such as iBF ₄ or a mixture of two or more thereof can be used. Further, as the solvent of the electrolyte solution, for example, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, tetrahydrofuran,
2-methyltetrahydrofuran, 1,3-dioxolane, sulfolane, acetonitrile, propionitrile,
Any one of methyl formate, methyl acetate, ethyl acetate, etc.
One kind or a mixture of two or more kinds can be used.

As the material of the battery can used in the present invention, stainless steel, nickel plated steel, etc. are used.
The shape is generally cylindrical or oval.

In the internal structure of the battery of the present invention, in particular, the non-aqueous battery, a metal foil having an active material and a binder attached to one or both sides is used as positive and negative electrodes, and the active materials are arranged to face each other via a separator. Rolled into a roll,
A cylindrical or elliptical wound product is inserted into a battery can, impregnated with a non-aqueous electrolyte solution, and sealed. At this time, it is necessary to expose the metal foil of either the positive electrode or the negative electrode to the outermost peripheral portion of the roll, and to bring the metal foil into contact with the battery can via a conductive spring.

[0020]

According to the present invention, the current collecting metal foil at the outermost periphery and the inner wall of the battery can can be surely brought into electrical contact with each other, and electric energy can be externally supplied without using a tab member. Can be taken out. Therefore, it is possible to provide a high-capacity battery that effectively uses the space inside the battery can.

[0021]

Embodiments of the present invention will now be described in detail and specifically with reference to the drawings, but these do not limit the scope of the present invention. In the examples and comparative examples described below, LiCoO ₂ used as the positive electrode active material was obtained by subjecting commercially available reagents CoO and LiCoO ₃ to heat treatment at 900 ° C. for 100 hours.

The positive electrode is made of the above-mentioned active material LiCoO.
_It was prepared by adding the same amount of a 5% DHF solution of polyvinylidene fluoride to a compound prepared by adding 5% of carbon-based conductive filler to ₂ to form a suspension, and uniformly applying the suspension to both sides of an aluminum foil. .. Coating amount is 300g per side
/ M ² .

The negative electrode has a true specific gravity of 2.
A 13% carbonaceous material crushed to an average particle size of about 10 μm was added with the same amount of a 5% solution of polyvinylidene fluoride in DHF to form a suspension, which was uniformly applied to one surface of a nickel foil or a copper foil. Created. The coating amount is 150 g / side
m ² .

Further, a polyethylene microporous film of 35 μm was used as the separator. The positive and negative electrode active materials thus obtained are made to face each other, and a separator is interposed between them so as to be wound in a roll shape to have an inner diameter of 15.5 m.
LiClO ₄ 0.6 after being put in a can of 50 m in height and 50 mm in height
It was impregnated with a ml / L propylene carbonate solution.

Example 1 A battery having the structure shown in FIG. 2 was prepared by using a copper foil as the negative electrode metal foil. The spring was made of hard copper having a thickness of 100 μm, a width of 7 mm, and a length of 95 mm, and was molded into a U shape as shown in FIG. 3 and inserted into the battery can. The results of measuring the impedance after impregnation are shown in Table 1.

Example 2 A battery having the structure shown in FIG. 2 was prepared by using nickel foil as the negative electrode metal foil. The spring was made of stainless steel having a thickness of 70 μm, a width of 15 mm, and a length of 40 mm, and one spring was inserted into the battery can. The results of measuring the impedance after impregnation are shown in Table 1.

Comparative Example 1 A battery having the structure shown in FIG. 1 was prepared by using a copper foil as the negative electrode metal foil. The results of measuring the impedance after impregnation are shown in Table 1.

[0028]

[Table 1]

[0029]

As is apparent from Table 1, the structure of the battery of the present invention has stable impedance, and stable electricity can be obtained through the wall of the battery can regardless of the conventional tab for taking out the battery. You can take it out and use the space inside the battery can effectively.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cross section of an outer peripheral portion of an electrode wound in a roll shape, which is a conventional technique.

FIG. 2 is a schematic view showing an embodiment of the present invention and showing a state of a conductive spring inserted in a gap between a negative electrode metal foil and a battery can.

FIG. 3 is a perspective view showing an embodiment of the present invention before inserting a can together with a conductive spring preformed in a U-shape together with a roll.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Positive electrode metal foil 4 Negative metal foil 5 Separator 6 Battery can 7 Spring 8 Roll 9 Positive electrode current collecting tab

Claims (1)

[Claims] 1. A battery structure constituted by winding a positive electrode and a negative electrode, each of which has an active material attached to a metal foil, wound in a roll so that the active material faces each other with a separator interposed therebetween. One of the positive electrode and the negative electrode has a metal foil exposed at the outermost periphery of the roll, and the metal foil is in contact with a battery can via a conductive spring.
Internal structure of the battery.